Project Summary/Abstract The link between both sleep problems and reward processing deficits have been well-established in depression; however, little research has examined the interplay of the two in conveying depression risk. Sleep problems are strongly implicated in not only the symptomatology of depression but also in its etiology and maintenance. Anhedonia, a hallmark of depression, is related to alterations in reward circuitry that leads to decreased reactivity to rewarding stimuli. Studies in healthy individuals have shown that decreased sleep disrupts reward processing, in particular by increasing reactivity to rewarding stimuli as well as decreasing motivation to pursue rewards. However, the role of insomnia in reward processing deficits associated with depression is less clear, and no studies have examined this relationship in the context of daily processes. In particular, although reward processing consists of unique and dissociable processes, comprising of anticipatory reward processing, consummatory reward processing, and motivation to recruit effort in the pursuit of reward, no study has attempted to delineate the relationship between insomnia and these separate reward- related components. Understanding of daily processes may be particularly critical in informing our understanding of the exact mechanisms through which risk for depression is conveyed. Thus, the current study proposes to characterize both between-person and within-person associations between insomnia and reward processing (Aim 1). Despite the large bodies of research on both reward-related deficits in depression and the role of sleep disturbance in depression and reward-processing, few attempts have been made to comprehensively examine the potential interplay between these two systems. Thus, this project will also examine how insomnia moderates the relationship between trait-level deficits in reward processing and momentary depressed mood (Aim 2). These aims will be tested using a sample of young adults aged 18-22 (N=145). The proposed study will include a baseline laboratory visit to assess trait-level reward processing function, chronic insomnia severity, and depressive symptoms, as well as utilize ecological momentary assessment and activity monitoring for 7 days to assess momentary depressed mood as well as daily objective sleep. The proposed project will advance the field by delineating the relationship between insomnia and multiple components of daily reward processes. Additionally, clarifying how insomnia and reward processing deficits interact with each other can provide a more unifying understanding of the development of depression risk.